Figure 4.

Growth assay of yeast on NSS. (a) Summary of the number of colony-forming units (CFU) per ml after an 8 h culture on NSS at 30°C. Each bar represents the average of five independent trials. The asterisks identify significance with p-values less than 0.05. Unshaded bars are uncoated (UC) samples, whereas shaded bars represent experimental data from Au-coated samples (Au). W303 showed a significant decrease in CFU ml⁻¹ when grown on both the UC and the Au-coated DD NSS, but not the lower aspect ratio Brd II NSS, whereas SK1 showed significant deficits in CFU count when grown on uncoated and coated DD and Brd II NSS. (b) An image of the typical culture plate set-up used in our CFU experiments. The surfaces (both control and NSS) were placed in a 24-well plate. All surfaces were coated with gold which altered the appearance of the surfaces—darkening the higher aspect ratio DD NSS, but increasing the reflectivity of the lower aspect ratio Brd II surface; this can be easily seen in the before (0 h) images. After 8 h of culture the control has been completely obscured by cells, whereas the NSS show varying degrees of obscurement with the dark DD NSS apparently lacking cell coverage relative to the controls (arrows).